1. Field of the Invention
The present invention relates to a visible image receiving material, a conductive pattern material and an organic electroluminescence element, which use a member having surface hydrophilicity. More particularly, the present invention relates to a visible image receiving material that is suitable for printing using an aqueous ink and excellent in coloring properties with respect to a colorant, a conductive pattern material that can conveniently form a conductive pattern and is useful for forming a circuit board, and an organic electroluminescence element that is excellent in sharpness of pixels and durability and can be conveniently subjected to uniform and local patterning.
2. Description of the Related Art
Various kinds of image receiving materials have been conventionally used in a printing apparatus using a general aqueous ink, and the image receiving materials are required to have such characteristics that an image thus formed has high chroma saturation, a colorant can be firmly fixed on the image receiving material, and the image receiving material is quick drying and does not cause ink blurring. In order to deal with such demands, the conventional image receiving materials for ink-jet recording use a polymer mordant in an image receiving layer. In this case, however, although an image thus formed has high chroma saturation and excellent transparency. there are problems such as in that absorptivity and drying speed of an ink are deteriorated, and an ink is liable to blur. Inorganic ultra-fine particles have also been used in image receiving layers, and in this case, while absorptivity and drying speed are excellent for avoiding ink blurring, there are problems such as in that an image thus formed has insufficient chroma saturation for brilliant color reproduction, and blurring occurs in the image upon storage thereof over a long period of time or under high humidity conditions.
As an example of the image receiving layer, which is excellent in physical characteristics, a colorant receiving layer having a three-dimensional network structure with a large porosity is disclosed in Japanese Patent Application Laid Open (JP-A) No. 7-276789. In this case, however, absorptivity of an ink and coloring properties in respect to a colorant are insufficient, and thus a visible image receiving material that is excellent in these characteristics is demanded.
Furthermore, various kinds of conductive pattern materials have been conventionally used for forming a circuit board. Representative examples thereof include those produced by forming a thin film of a conductive material on an insulating material by a known method, such as vacuum deposition, subjecting the thin film is subjected to a resist treatment, removing a part of the resist thus formed by pattern exposure, and then carrying out an etching treatment to form a desired pattern. Such a process requires at least four process steps, and a treating step for a waste liquid is also required in the case where a wet etching treatment is carried out. Complicated process steps are thus required.
As an example using another method for forming a pattern for a conductive pattern, a material for forming a conductive pattern by using a photoresist is known. In this method, a substrate having a photoresist polymer coated thereon or having a photoresist provided on a dry film attached thereto is exposed with UV light through an arbitrary photomask to form a pattern, such as a lattice shape, and the method is useful for forming an electromagnetic wave shield requiring high conductivity.
In recent years, a method for forming a pattern directly from digital data without use of a photomask is receiving attention as a conductive pattern material, and various kinds of proposals have been made.
It is expected that an arbitrary pattern can be conveniently formed by utilizing such digitalized pattern forming. Examples of the method include a method utilizing a self-assembling monomolecular film. This method utilizes a molecular aggregate that is spontaneously formed upon immersing a substrate in an organic solvent containing a surface active molecule, and examples thereof include a combination of an organic silane compound with an SiO2 substrate or an Al2O3 substrate, and a combination of an alcohol or an amine with a platinum substrate, which can be patterned, for example, by a photolithography process. Although the monomolecular film enables formation of a fine pattern, it is necessary to use the restricted combinations of substrates and materials, and thus the method is difficult to apply in practical use. Therefore, presently, that such a technique for forming a conductive pattern, such as wiring, that can be practically applied has not yet been established.
Furthermore, research and development relating to various kinds of display elements are being actively carried out, and among them, an organic electroluminescence element (hereinafter, also referred to as an “organic EL element”) is receiving attention owing to light emission of high luminance with a low voltage. In particular, the element is expected to realizing a full color display element having a large area.
To realize a full color organic EL element, it is presently necessary to arrange organic light emitting layers emitting light of three primary colors, red, green and blue, for the respective pixels, and as a production process of such a full color organic EL element, such methods as a patterning method of an EL element by a lithography process, a patterning method by vapor deposition, and a patterning method by a conventional printing method, such as screen printing, with a printing ink containing an EL material, have been employed.
However, the technique of patterning the organic light emitting layer has significant problems with regard to accuracy. The reasons therefor are as follows. The metal surface of the reflective electrode material is unstable, and thus patterning by vapor deposition fails to achieve sufficient accuracy. The polymer and the precursor for forming a positive hole injection layer and an organic light emitting layer cannot withstand patterning processes, such as photolithography.
In order to solve the aforementioned problems, JP-A No. 10-153967 discloses an EL display device capable of exerting full color display in which a resin black resist is formed between transparent pixel electrodes by a photoresist process, and light emitting materials corresponding to the respective light emitting pixels are contained in ink liquids by using the resin black resist as a partition, and which is applied by the ink-jet method, as well as a production process of the EL display device.
However, because a blue light emitting material assuring durability and reliability cannot be prepared as a conventional PPV series aqueous solution precursor, organic light emitting layers of red and green colors are patterned for respective pixels by the ink-jet method, and a charge transporting organic light emitting layer of blue color is formed as an adjacent layer by a vacuum deposition method.
Furthermore, JP-A No. 10-12377 as an example of a process using no partition between pixels upon patterning the organic light emitting layers of three colors for the respective pixels by the inkjet method, discloses the following process. A positive hole injection layer is formed as an upper layer of a transparent pixel electrode formed on a glass substrate having thin film transistors formed thereon, and the organic light emitting layers corresponding to the respective pixels are formed as an upper layer of the positive hole injection layer by the ink-jet method.
However, there is a problem in accuracy of spotting ink droplets at positions of the pixels corresponding to the respective colors, and there is also a problem in that the liquid droplets are expanded and contracted during drying, whereby proper performance of the EL display cannot be exerted due to overlap of and gaps between the respective light emitting layers.
Furthermore, in the foregoing techniques, there is no particular consideration of adhesion between the organic compound layer, on which the pixels are formed, and a lower layer (such as a substrate), and therefore, there is a defect in that the organic compound layer is liable to be peeled off.
Under the circumstances described in the foregoing, it is difficult uniformly attain both sharpness and durability of the pixels and local patterning for the respective colors, in the organic EL element.